Online detection method and apparatus for battery leakage risk

Abstract

The present disclosure provides an online detection method and apparatus for a battery leakage risk. The method comprises: when a current insulation resistance value is reduced to a risk insulation resistance value, determining a reference resistance value reduction value on the basis of reference resistance value change rates and actual process durations under different states of charge; if the reference resistance value reduction value is smaller than the risk insulation resistance value, then when the current insulation resistance value is reduced by a preset resistance value, determining an actual interval resistance value reduction rate in this instance of resistance value reduction; comparing the actual interval resistance value reduction rate with a corresponding reference interval resistance value reduction rate in a reference curve, and on the basis of the comparison result, determining an interval leakage risk corresponding to this instance of resistance value reduction ; repeatedly performing the step of determining the actual interval resistance value reduction rate in this instance of resistance value reduction; and on the basis of interval leakage risks, determining a final battery leakage risk of a battery pack to be tested. By using the described online detection method and apparatus for the battery leakage risk, the problem of relatively high detection costs of battery leakage risks is solved.

Description

An online detection method and device for battery leakage risk

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202311035274.X filed with the Patent Office of China on August 16, 2023, entitled “A method and device for online detection of battery leakage risk,” the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present disclosure relates to the field of battery technology, and in particular to an online detection method and device for battery leakage risk. Background Art

[0004] Currently, new energy vehicles are increasingly popular among consumers. These vehicles are powered by lithium-ion battery packs, which consist of dozens or even hundreds of cells connected in parallel and in series. The lithium-ion battery industry is currently developing rapidly, but the production process is still immature. If the diaphragm of a lithium-ion battery is wrinkled during production, or if mechanical damage or foreign matter is present, the insulating film may break, causing the negative electrode to overlap with the housing. Furthermore, production defects such as overlap between the negative electrode aluminum wire and the housing, or exposed adapters in contact with the housing, can cause the battery housing to be gradually corroded by the electrolyte, ultimately leading to battery leakage. When leakage occurs within the battery pack, the volatilization of the electrolyte can corrode the pack, and the electrolyte is flammable. If sparks occur within the battery pack, there is a risk of fire and explosion.

[0005] However, the existing technology mainly adopts the method of disassembling the battery pack and manually observing to detect battery leakage, or adding a gas sensor to detect whether the battery pack is leaking. However, disassembling the battery pack and adding a gas sensor will increase the detection cost of the battery leakage risk.

[0006] Summary of the Invention

[0007] In view of this, an object of the present disclosure is to provide an online detection method and device for battery leakage risk, so as to solve the problem of high cost of battery leakage risk detection in the prior art.

[0008] In a first aspect, an embodiment of the present disclosure provides an online detection method for battery leakage risk, comprising:

[0009] The current insulation resistance of the battery pack to be tested is obtained online. When the current insulation resistance drops to the risk insulation resistance, the reference resistance reduction value is determined based on the reference resistance change rate at different states of charge and the actual process duration corresponding to different states of charge during the resistance reduction process.

[0010] Compare the reference resistance reduction value with the risk insulation resistance value. If the reference resistance reduction value is less than the risk insulation resistance value, then when the current insulation resistance value is reduced by a preset resistance value, determine the actual interval resistance reduction rate corresponding to the current resistance reduction process.

[0011] Compare the actual resistance reduction rate with the corresponding reference resistance reduction rate in the reference curve, and determine the leakage risk of the interval corresponding to this resistance reduction process based on the comparison result;

[0012] If the judgment condition is not met, the insulation resistance value after the preset resistance value is reduced is used as the new current insulation resistance value, and the process returns to the step of determining the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance value is reduced by the preset resistance value;

[0013] When the judgment conditions are met, the final battery leakage risk of the battery pack to be tested is determined based on the interval leakage risks corresponding to the multiple resistance reduction processes.

[0014] Optionally, a reference resistance reduction value is determined based on the reference resistance change rate under different charge states and the actual process duration under different charge states during the resistance reduction process, including: for each charge state, determining the product of the reference resistance change rate corresponding to the charge state and the actual process duration corresponding to the charge state; and taking the sum of the products under different charge states as the reference resistance reduction value.

[0015] Optionally, the reference curve includes a first reference curve and a second reference curve, the first reference curve includes a first reference interval resistance reduction rate corresponding to the current resistance reduction process, the second reference curve includes a second reference interval resistance reduction rate corresponding to the current resistance reduction process, the state of charge corresponding to the first reference curve is higher than the state of charge corresponding to the second reference curve, and the interval leakage risk corresponding to the current resistance reduction process is determined based on the comparison result, including: if the actual interval resistance reduction rate is less than the second reference interval resistance reduction rate, determining that the interval leakage risk of the current resistance reduction process is low; if the actual interval resistance reduction rate is less than the first reference interval resistance reduction rate and greater than or equal to the second reference interval resistance reduction rate, determining that the interval leakage risk of the current resistance reduction process is medium; if the actual interval resistance reduction rate is greater than or equal to the first reference interval resistance reduction rate, determining that the interval leakage risk of the current resistance reduction process is high.

[0016] Optionally, determining the actual interval resistance reduction rate corresponding to the current resistance reduction process includes: taking a ratio of a preset resistance value to a duration required for the current resistance reduction process as the actual interval resistance reduction rate.

[0017] Optionally, after comparing the reference resistance reduction value with the risk insulation resistance value, it also includes: if the ratio of the reference resistance reduction value to the risk insulation resistance value is less than a set threshold, determining whether the voltage and temperature of the battery cell in the battery pack to be tested are the set values; if they are the set values, determining that there is a sealing problem in the battery pack to be tested; if it is not the set values, determining that there is a battery leakage risk in the battery pack to be tested, so as to further determine the severity of the leakage risk.

[0018] Optionally, the method further includes: if the reference resistance reduction value is greater than or equal to the risk insulation resistance value, the severity of the final battery leakage risk of the battery pack to be tested is low.

[0019] Optionally, before obtaining the current insulation resistance of the battery pack to be tested online, the method also includes: obtaining multiple defective batteries with leakage risk, adjusting the multiple defective batteries to different charge states and packaging them separately to obtain defective battery packs with different charge states; for each defective battery pack, monitoring the insulation resistance of the defective battery pack, and recording the theoretical total time required for the defective battery pack to reduce from the initial insulation resistance to the target insulation resistance, the theoretical resistance change value of the reduction process, and the theoretical interval time required for each reduction in the preset resistance; determining the reference resistance change rate of the charge state corresponding to the defective battery pack based on the theoretical total time and the theoretical resistance change value; and determining the reference curve corresponding to the defective battery pack based on the theoretical interval time and the preset resistance value.

[0020] Optionally, the method also includes: when the current insulation resistance value is reduced to the risk insulation resistance value, determining the actual resistance change rate based on the total insulation resistance change value during the reduction process and the time required for the reduction process; comparing the actual resistance change rate with the reference resistance change rate, and determining the battery leakage risk of the battery pack to be tested based on the comparison result.

[0021] Optionally, the method also includes: updating the reference curve using the actual interval resistance reduction rate of the battery pack to be tested during different resistance reduction processes; and updating the reference resistance change rate using the actual resistance change rate during the process of the current insulation resistance being reduced to the risk insulation resistance.

[0022] In a second aspect, an embodiment of the present disclosure further provides an online detection device for battery leakage risk, the device comprising:

[0023] The theoretical value calculation module is used to obtain the current insulation resistance of the battery pack to be tested online. When the current insulation resistance drops to the risk insulation resistance, the reference resistance reduction value is determined based on the reference resistance change rate under different charge states and the actual process duration corresponding to different charge states during the resistance reduction process;

[0024] A numerical comparison module is used to compare the reference resistance reduction value with the risk insulation resistance value. If the reference resistance reduction value is less than the risk insulation resistance value, then when the current insulation resistance value is reduced by a preset resistance value, the actual interval resistance reduction rate corresponding to the current resistance reduction process is determined;

[0025] The interval risk determination module is used to compare the actual interval resistance reduction rate with the reference interval resistance reduction rate in the reference curve, and determine the interval leakage risk corresponding to the current resistance reduction process based on the comparison result;

[0026] a loop calculation module, configured to, when the judgment condition is not met, use the insulation resistance after the preset resistance is reduced as the new current insulation resistance, and return to the step of determining the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance is reduced by the preset resistance;

[0027] The comprehensive risk determination module is used to determine the final battery leakage risk of the battery pack to be tested based on the interval leakage risk corresponding to multiple resistance reduction processes when the judgment conditions are met.

[0028] The embodiments of the present disclosure bring the following beneficial effects:

[0029] An online detection method and device for battery leakage risk provided by the embodiments of the present disclosure can use the acquired current insulation resistance value to determine online the actual interval resistance reduction rate of the battery pack to be tested each time the preset resistance value is reduced, and use the comparison results of the actual interval resistance reduction rate and the reference interval resistance reduction rate to perform non-destructive detection of leakage risk, thereby realizing online non-destructive testing without disassembling the battery pack or using professional testing equipment, thereby reducing testing costs. Compared with the online detection method for battery leakage risk in the prior art, the device solves the problem of high detection cost of battery leakage risk.

[0030] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0032] FIG1 shows a flow chart of an online detection method for battery leakage risk provided by an embodiment of the present disclosure;

[0033] FIG2 shows a schematic structural diagram of an online detection device for battery leakage risk provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the disclosure for which protection is sought, but merely represents selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, every other embodiment obtained by those skilled in the art without making creative work falls within the scope of protection of the present disclosure.

[0035] It is worth noting that before the present disclosure was made, new energy vehicles are becoming more and more popular among consumers. New energy vehicles use lithium-ion battery packs for power supply. The battery packs are composed of dozens or hundreds of batteries connected in parallel and in series. The current lithium-ion battery industry is developing rapidly, but the production process still has the problem of immaturity. If the diaphragm of the lithium-ion battery is wrinkled during the production process, mechanical damage, foreign matter, etc., it may cause the insulating film to break, resulting in overlapping of the negative electrode sheet and the shell. At the same time, production defects such as overlapping of the negative electrode aluminum wire and the shell, and exposed contact of the adapter with the shell will cause the battery shell to be gradually corroded by the electrolyte, and eventually cause battery leakage. When battery leakage occurs in the battery pack, the volatilization of the electrolyte will corrode the battery pack, and the electrolyte is flammable. Once a spark occurs in the battery pack, there is a risk of fire and explosion. However, the existing non-vehicle-side online detection method mainly uses the method of manual observation after disassembling the battery pack to detect battery leakage, or adds a gas sensor to detect whether the battery pack is leaking. However, disassembling the battery pack and adding a gas sensor will increase the detection cost of the battery leakage risk.

[0036] Based on this, an embodiment of the present disclosure provides an online detection method for battery leakage risk, so as to reduce the detection cost of battery leakage risk.

[0037] Please refer to Figure 1, which is a flow chart of an online detection method for battery leakage risk provided by an embodiment of the present disclosure. As shown in Figure 1, the online detection method for battery leakage risk provided by an embodiment of the present disclosure includes:

[0038] Step S101, online acquisition of the current insulation resistance of the battery pack to be tested. When the current insulation resistance drops to a risk insulation resistance, the reference resistance reduction value is determined based on the reference resistance change rate under different charge states and the actual process duration corresponding to the different charge states during the resistance reduction process.

[0039] In this step, the battery pack to be tested may refer to a battery pack carried on a mobile vehicle, and the battery pack to be tested is used to provide power for the mobile vehicle.

[0040] Exemplarily, the battery pack to be tested may be a lithium battery pack.

[0041] For example, the mobile vehicle may be a new energy vehicle or other mobile device powered by a battery pack.

[0042] The current insulation resistance value may refer to the insulation resistance value of the battery pack to be tested. The current insulation resistance value represents the current insulation capability of the battery pack to be tested. The insulation resistance value of the battery pack to be tested may be reduced due to leakage.

[0043] The risk insulation resistance value may refer to a set insulation resistance value threshold. When the current insulation resistance value of the battery pack to be tested drops to the risk insulation resistance value, it indicates that the current insulation resistance value of the battery pack to be tested is low and there may be a risk of leakage.

[0044] For example, the risk insulation resistance value can be 1 / 2 or 1 / 3 of the initial insulation resistance value of the battery pack to be tested. Those skilled in the art can select a specific value for the risk insulation resistance value based on actual conditions, and this disclosure does not limit this. The initial insulation resistance value is the insulation resistance value of the battery pack to be tested when it leaves the factory.

[0045] The state of charge (SOC) may refer to the remaining capacity (State Of Charge, SOC) of the battery pack to be tested.

[0046] Exemplarily, the different states of charge may be a low state of charge, a medium state of charge, and a high state of charge. It should be noted that the different states of charge are not fixed to three states of charge, but may be other numbers of states of charge, which is not limited in the present disclosure.

[0047] In the embodiment of the present disclosure, taking three states of charge as an example, the remaining power in the range of [0%, 30%] can be regarded as a low state of charge, the remaining power in the range of (30%, 80%] can be regarded as a medium state of charge, and the remaining power in the range of (80%, 100%] can be regarded as a high state of charge.

[0048] The reference resistance change rate may refer to the insulation resistance change rate obtained through experiments, that is, the speed at which the insulation resistance decreases per unit time.

[0049] The actual process duration may refer to the time taken for the insulation resistance value to change and for the insulation resistance value to decrease to the risk insulation resistance value when the battery pack to be tested is tested online.

[0050] In the disclosed embodiment, assuming that the insulation resistance of the battery pack under test begins to decrease at 10:00 AM and decreases to the risk insulation resistance by 11:00 AM, the actual process duration is one hour. However, the state of charge of the battery under test varies during this hour, with a low state of charge duration of 20 minutes, a medium state of charge duration of 30 minutes, and a high state of charge duration of 10 minutes. Therefore, the actual process duration corresponding to different states of charge during this resistance reduction process can be divided into low state of charge duration, medium state of charge duration, and high state of charge duration.

[0051] The reference resistance reduction value is a theoretical value of insulation resistance reduction in the process of reducing the current insulation resistance to the risk insulation resistance, that is, a theoretical amplitude of insulation resistance reduction in the process of resistance reduction.

[0052] In the disclosed embodiments, battery leakage risk detection can be performed on battery packs installed in new energy vehicles. These battery packs are referred to as the battery packs to be tested. Regardless of whether the new energy vehicle is in driving, charging, discharging, or stationary, the disclosed embodiments can perform online testing for the battery leakage risk of the battery packs to be tested, achieving real-time and rapid determination of battery leakage risk.

[0053] Here, the battery pack to be tested is divided into two situations in actual use conditions: one is that the whole vehicle is in an upper high-voltage state, at this time the insulation resistance calculated by the battery management system (BMS) is the insulation resistance after the battery pack to be tested and the whole vehicle system are connected. When there is an insulation problem with the whole vehicle, it will also cause the insulation resistance calculated by the BMS to be low. The other is that the whole vehicle is in a lower high-voltage state, at this time the insulation resistance calculated by the BMS is the insulation resistance in the battery pack to be tested. Therefore, in order to prevent the influence of the insulation problem of the whole vehicle on the monitoring method, data preprocessing is required to exclude the influence of the insulation value of the non-battery pack.

[0054] Here, the vehicle status can be judged by the vehicle motor voltage or the battery pack contactor status to determine whether the battery pack to be tested is connected to the vehicle system. If the vehicle motor voltage and the battery pack voltage are equal, it is determined that the vehicle status is in the upper high-voltage state. In addition, if the battery pack contactor status is closed, it can also be determined that the vehicle status is in the upper high-voltage state. At this time, the battery pack to be tested and the vehicle system are connected. If the vehicle status always remains in the upper high-voltage state, the change in insulation resistance cannot be directly used to detect the risk of battery leakage. Only when the vehicle status has passed the lower high-voltage state can the data collected by the BMS be used. When the above prerequisites are met, the insulation data of the battery pack to be tested can be obtained through the BMS system. The insulation data includes the current insulation resistance of the battery pack to be tested.

[0055] After obtaining the current insulation resistance value, track and monitor its changes to determine whether it has decreased. Assuming the initial insulation resistance of the battery pack to be tested is 10,000 kΩ, select half of the initial insulation resistance, or 5,000 kΩ, as the risk insulation resistance value. If the current insulation resistance value decreases to 5,000 kΩ, the battery leakage risk calculation begins.

[0056] First, reference resistance change rates at different states of charge are obtained. The reference resistance change rates at different states of charge include: a first reference resistance change rate corresponding to a high state of charge, a second reference resistance change rate corresponding to a medium state of charge, and a third reference resistance change rate corresponding to a low state of charge. Then, the duration of the first process in the high state of charge, the duration of the second process in the medium state of charge, and the duration of the third process in the low state of charge are determined, respectively, during the total duration of the process from the beginning of the current insulation resistance decrease to the decrease to 5000 kΩ. Based on the first reference resistance change rate, the second reference resistance change rate, the third reference resistance change rate, the duration of the first process, the duration of the second process, and the duration of the third process, a reference resistance reduction value is calculated. For example, the product of each reference resistance change rate and the corresponding process duration is calculated, and the weighted sum of the three products is used as the reference resistance reduction value.

[0057] Step S102 : comparing the reference resistance reduction value with the risk insulation resistance; if the reference resistance reduction value is less than the risk insulation resistance, determining the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance is reduced by a preset resistance value.

[0058] In this step, the reference resistance reduction value represents the reference value of the resistance reduction of the battery under test as it decreases to the risk insulation value. This reference resistance reduction value cannot be directly used to determine the leakage risk of the battery under test. It needs to be compared with the risk insulation resistance value. If the reference resistance reduction value is greater than or equal to the risk insulation resistance value, it means that the actual resistance reduction is slower than the reference resistance reduction value, and the severity of the battery leakage risk is low. Conversely, if the reference resistance reduction value is less than the risk insulation resistance value, further assessment of the specific battery leakage risk is required.

[0059] The preset resistance value may refer to a set resistance reduction range. For example, taking a new energy vehicle as an example, the preset resistance value corresponding to the battery pack to be tested may be 100KΩ.

[0060] The actual interval resistance reduction rate may refer to the speed at which the insulation resistance decreases during the process in which the battery pack to be tested decreases the preset resistance.

[0061] In order to more accurately detect the risk of battery leakage, the actual interval resistance reduction rate during the decline process can be calculated every time the insulation resistance of the battery pack to be tested drops by 100KΩ, so as to determine the interval leakage risk based on the actual interval resistance reduction rate.

[0062] In the disclosed embodiment, the preset resistance value is denoted as d, and the time required for a single resistance reduction process is denoted as Δt. For a single resistance reduction process, the actual resistance reduction rate within the corresponding interval can be calculated using d and Δt. For example, the value is (d + Δd) / Δt, where Δd is the resistance fluctuation value.

[0063] Step S103 : comparing the actual interval resistance reduction rate with the corresponding reference interval resistance reduction rate in the reference curve, and determining the interval leakage risk corresponding to the current resistance reduction process according to the comparison result.

[0064] In this step, the reference curve may refer to a curve used for comparison with the actual interval resistance reduction rate. The reference curve includes multiple reference interval resistance reduction rates. Each reference interval resistance reduction rate is a point on the reference curve, and each point represents a staged resistance reduction rate in the process of reducing the insulation resistance to a preset resistance value of 100KΩ.

[0065] Assume that the entire reference curve is used to describe the process of insulation resistance decreasing from 5000KΩ to 1000KΩ, and the preset resistance is 100KΩ. Then, during the entire resistance reduction process, there are a total of (5000-1000) / 100=40 intervals on the reference curve. Each interval is an interval resistance reduction process corresponding to an insulation resistance reduction by the preset resistance value. The entire resistance reduction process has a total of 40 interval resistance reduction processes. Each interval corresponds to a reference interval resistance reduction rate. The reference interval resistance reduction rate describes the speed at which the resistance decreases within the corresponding interval.

[0066] Interval leakage risk may refer to the leakage risk during the process of the primary insulation resistance decreasing to a preset resistance value.

[0067] In the embodiment of the present disclosure, taking the resistance reduction process from 1000KΩ to 900KΩ as an example, the actual resistance reduction rate of the resistance reduction process is ν act , then determine the reference interval resistance reduction rate ν corresponding to the interval from 1000KΩ to 900KΩ from the reference curve ref , ν act with ν ref For comparison, according to ν act with ν ref The comparison results determine the leakage risk of the interval corresponding to this resistance reduction process.

[0068] Step S104, when the judgment condition is not met, the insulation resistance after the preset resistance is reduced is used as the new current insulation resistance, and the process returns to the step of determining the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance is reduced by the preset resistance.

[0069] In this step, the judgment condition may refer to a condition for determining the final battery leakage risk. After multiple resistance reduction processes, it may be determined based on the judgment condition whether to make a final battery leakage risk judgment on the battery pack to be tested.

[0070] For example, the judgment condition may be that the number of resistance reduction processes reaches a threshold number, the judgment condition may be that the current insulation resistance is less than a set threshold, or the judgment condition may be that the number of leakage risks in multiple intervals reaches a set risk.

[0071] In the embodiment of the present disclosure, taking the judgment condition that the number of resistance reduction processes reaches the number threshold as an example, if the number of resistance reduction processes does not reach the number threshold, it is necessary to continue to determine the interval leakage risk of the next resistance reduction process. At this time, the insulation resistance after reducing the preset resistance value can be used as the new current insulation resistance value to repeat the process of determining the actual interval resistance reduction rate corresponding to this resistance reduction process until the judgment condition is met, and the loop execution process is stopped.

[0072] Step S105 : When the judgment condition is met, the final battery leakage risk of the battery pack to be tested is determined according to the interval leakage risks corresponding to the multiple resistance reduction processes.

[0073] In an embodiment of the present disclosure, if the number of resistance reduction processes reaches a threshold number, the final battery leakage risk of the battery pack to be tested is determined based on the interval leakage risks corresponding to the multiple resistance reduction processes. For example, the average risk of leakage risks in multiple intervals is determined, and the average risk is used as the final battery leakage risk of the battery pack to be tested.

[0074] For example, the interval leakage risk is divided into low, medium and high. The value corresponding to low risk is 1, the value corresponding to medium risk is 1, and the value corresponding to high risk is 3. If there are 10 interval leakage risks in total, the final battery leakage risk is determined based on the average value of the values ​​corresponding to these 10 interval leakage risks.

[0075] In an optional embodiment, a reference resistance reduction value is determined based on a reference resistance change rate under different charge states and an actual process duration under different charge states during the resistance reduction process, including: for each charge state, determining the product of the reference resistance change rate corresponding to the charge state and the actual process duration corresponding to the charge state; and taking the sum of the products under different charge states as the reference resistance reduction value.

[0076] Specifically, taking the low, medium, and high SOC states as an example, the reference resistance change rate corresponding to the high SOC is V1, and the actual process duration is T1; the reference resistance change rate corresponding to the medium SOC is V2, and the actual process duration is T2; and the reference resistance change rate corresponding to the low SOC is V3, and the actual process duration is T3. The reference resistance reduction value is recorded as: △R, then △R = V1×T1+V2×T2+V3×T3.

[0077] In an optional embodiment, the reference curve includes a first reference curve and a second reference curve, the first reference curve includes a resistance reduction rate in a first reference interval corresponding to the current resistance reduction process, the second reference curve includes a resistance reduction rate in a second reference interval corresponding to the current resistance reduction process, the state of charge corresponding to the first reference curve is higher than the state of charge corresponding to the second reference curve, and the leakage risk of the interval corresponding to the current resistance reduction process is determined based on the comparison result, including: steps A1 to A3.

[0078] In step A1, if the actual interval resistance reduction rate is less than the second reference interval resistance reduction rate, it is determined that the interval leakage risk of the current resistance reduction process is low.

[0079] The reference curves include a first reference curve corresponding to a high state of charge, a second reference curve corresponding to a medium state of charge, and a third reference curve corresponding to a low state of charge. Assuming that the resistance value decreases from 1000KΩ to 900KΩ, the first reference curve includes the resistance value decrease rate ν in the first reference interval corresponding to the process of decreasing from 1000KΩ to 900KΩ. ref_1 The second reference curve includes the second reference interval resistance reduction rate ν corresponding to the process of decreasing from 1000KΩ to 900KΩ ref_2 The third reference curve includes the third reference interval resistance reduction rate ν corresponding to the process of decreasing from 1000KΩ to 900KΩ ref_3 .

[0080] If ν act <ν ref_2 , it is determined that the leakage risk in the process of reducing from 1000KΩ to 900KΩ is low risk.

[0081] In step A2, if the actual interval resistance reduction rate is less than the first reference interval resistance reduction rate and greater than or equal to the second reference interval resistance reduction rate, the interval leakage risk of this resistance reduction process is determined to be medium.

[0082] If ν ref_2 ≤ν act <ν ref_1 , it is determined that the leakage risk in the process of decreasing from 1000KΩ to 900KΩ is medium risk.

[0083] Step A3: If the actual interval resistance reduction rate is greater than or equal to the first reference interval resistance reduction rate, it is determined that the leakage risk of the interval where the resistance is reduced this time is high.

[0084] If ν ref_1 ≤ν act , it is determined that the leakage risk in the process of decreasing from 1000KΩ to 900KΩ is high risk.

[0085] In an optional embodiment, determining the actual interval resistance reduction rate corresponding to the current resistance reduction process includes: taking a ratio of a preset resistance value to a duration required for the current resistance reduction process as the actual interval resistance reduction rate.

[0086] Assume that the preset resistance is 100KΩ, and it takes 100 minutes to reduce the resistance by 100KΩ during a resistance reduction process. The actual resistance reduction rate in the interval is 1KΩ / minute.

[0087] In an optional embodiment, after comparing the reference resistance reduction value with the risk insulation resistance, the method further includes: steps B1 to B3.

[0088] Step B1: If the ratio of the reference resistance reduction value to the risk insulation resistance value is less than a set threshold, determine whether the voltage and temperature of the battery cell in the battery pack to be tested are set values.

[0089] The battery pack under test is inherently waterproof and well-sealed. However, after repair or damage, the seal may be compromised. In this case, if the vehicle wades through water, water may enter the battery pack under test, causing a decrease in the insulation resistance of the battery pack under test. Therefore, it is necessary to rule out the possibility that the insulation resistance of the battery pack under test has decreased due to wading. Here, you can determine whether the battery pack under test has been flooded by following the steps below.

[0090] Calculate the ratio of the reference resistance reduction value △R to the risk insulation resistance value of 5000KΩ. If the ratio is less than the set threshold value 0.01, it means that the reference resistance reduction value △R is much smaller than the risk insulation resistance value, and further judgment is needed on the voltage and temperature of the battery cell.

[0091] Step B2: If the value is the set value, it is determined that the battery pack to be tested has a sealing problem.

[0092] If the voltages and temperatures of multiple modules within the battery pack being tested are all at the initialization value or the disconnection value, it indicates that the battery pack has been flooded or its seal is poor due to other reasons. In this case, the risk of battery leakage cannot be confirmed. The set values ​​are the initialization values ​​or the disconnection value, both of which are known quantities.

[0093] In step B3, if the value is not the set value, it is determined that the battery pack to be tested has a risk of battery leakage, so as to further determine the severity of the leakage risk.

[0094] If the voltages and temperatures of multiple module cells in the battery pack to be tested are not the initialized values ​​or disconnection values, it indicates that the battery pack to be tested is well sealed and the packaging is not damaged. There may be a risk of battery leakage, and the severity of the leakage risk needs to be further determined.

[0095] In an optional embodiment, the method further includes: if the reference resistance reduction value is greater than or equal to the risk insulation resistance value, the severity of the final battery leakage risk of the battery pack to be inspected is low.

[0096] If the reference resistance reduction value △R ≥ 5000KΩ, it indicates that although the actual resistance reduction value should theoretically be lower than 5000KΩ, the actual resistance reduction value has just reached 5000KΩ. The actual resistance reduction value is higher than the expected reference resistance reduction value, indicating that the actual resistance reduction rate is slower. Therefore, the severity of the final battery leakage risk of the battery pack to be tested is determined to be low.

[0097] In an optional embodiment, before obtaining the current insulation resistance of the battery pack to be tested online, the method further includes: steps C1 to C4.

[0098] Step C1: obtain multiple defective batteries with leakage risks, adjust the multiple defective batteries to different states of charge, and package them separately to obtain defective battery packs with different states of charge.

[0099] Before conducting online battery leakage risk testing, it is necessary to determine the reference resistance change rate and reference curve. To this end, a number of defective batteries with leakage risks can be selected from batteries actually produced on the production line in the laboratory. Defective batteries with leakage risks include batteries with overlapping defects between the negative electrode sheet and the battery casing, batteries with overlapping defects between the negative electrode aluminum wire and the casing, and batteries with exposed adapters and contact defects with the casing.

[0100] Multiple defective batteries with leakage risks are adjusted to different charge states. For example, if there are three defective batteries, these three defective batteries are adjusted to low charge state, medium charge state and high charge state respectively. Then, each defective battery after the charge state is adjusted is packaged to obtain multiple defective battery packs.

[0101] Step C2: For each defective battery pack, monitor the insulation resistance of the defective battery pack, record the theoretical total time required for the defective battery pack to reduce from the initial insulation resistance to the target insulation resistance, the theoretical resistance change value during the reduction process, and the theoretical interval time required for each reduction in the preset resistance.

[0102] Place multiple defective battery packs in a static state, continuously monitor the changes in the insulation resistance of the defective battery packs in the static state, and record the time required for each defective battery pack to reduce its initial insulation resistance to 10KΩ. This time is the theoretical total time, recorded as: T the The total resistance change of each defective battery pack from the initial insulation resistance to 10KΩ is also recorded, that is, the theoretical resistance change, recorded as: △R the The time required for each defective battery pack to reduce its insulation resistance from the initial value to 10KΩ by 100KΩ is also recorded, that is, the theoretical interval time, recorded as: T interval 100KΩ is a preset resistance value, which can be calculated based on the initial insulation resistance value of the defective battery pack. For example, the value obtained by dividing the initial insulation resistance value by 100 is used as the preset resistance value.

[0103] Step C3: Determine a reference resistance change rate of the state of charge corresponding to the defective battery pack based on the theoretical total time and the theoretical resistance change value.

[0104] For each defective battery pack, the theoretical resistance change value △R of the defective battery pack is calculated. the The theoretical total duration T of the defective battery pack the The ratio of is used as the reference resistance change rate of the charge state corresponding to the defective battery pack. If the defective battery pack is in a low charge state, the calculated reference resistance change rate is the reference resistance change rate of the low charge state.

[0105] Step C4: Determine the reference curve corresponding to the defective battery pack based on the theoretical interval duration and the preset resistance value.

[0106] Here, the initial insulation resistance is recorded as: ndKΩ, and the preset resistance is ndKΩ / n=dKΩ=100KΩ. For each defective battery pack, calculate the dKΩ / T of each of the k+1 intervals of [ndKΩ, (n-1)dKΩ], [(n-1)dKΩ, (n-2)dKΩ], [(n-2)dKΩ, (n-3)dKΩ]…[(nk)dKΩ, 10KΩ]. interval_i The ratio of the reference interval resistance reduction rate is the reference interval resistance reduction rate of the interval. The reference interval resistance reduction rates of different intervals are interpolated to generate a curve with the horizontal axis as time and the vertical axis as the reference interval resistance reduction rate. This curve is the reference curve of the defective battery pack.

[0107] In an optional embodiment, the method further includes: when the current insulation resistance value is reduced to the risk insulation resistance value, determining the actual resistance change rate based on the total insulation resistance change value during the reduction process and the time required for the reduction process; comparing the actual resistance change rate with the reference resistance change rate, and determining the battery leakage risk of the battery pack to be tested based on the comparison result.

[0108] In addition, during the actual battery leakage risk monitoring process, when the current insulation resistance drops to the risk insulation resistance of 5000kΩ, the ratio of the actual total insulation resistance change value during the process to the duration required for the process is calculated. This ratio is used as the actual resistance change rate, and the actual resistance change rate is compared with the reference resistance change rate.

[0109] If the ratio of the actual resistance change rate to the reference resistance change rate is greater than a first ratio threshold, the battery leakage risk is determined to be high risk; if the ratio of the actual resistance change rate to the reference resistance change rate is less than a second ratio threshold, the battery leakage risk is determined to be low risk; if the ratio of the actual resistance change rate to the reference resistance change rate is greater than or equal to the second ratio threshold and less than or equal to the first ratio threshold, the battery leakage risk is determined to be medium risk. The first ratio threshold is greater than the second ratio threshold.

[0110] In an optional embodiment, the method further includes: updating the reference curve using the actual interval resistance reduction rate of the battery pack to be tested during different resistance reduction processes; and updating the reference resistance change rate using the actual resistance change rate during the process of the current insulation resistance being reduced to the risk insulation resistance.

[0111] After determining the battery leakage risk of the battery pack to be tested, the reference curve can be updated based on the test results. Specifically, the battery leakage risk test results of multiple battery packs to be tested for different new energy vehicles can be obtained, and the test results of battery packs with battery leakage risks can be summarized.

[0112] For each state of charge, determine the actual interval resistance reduction rate of the same resistance reduction interval for the same model defective battery pack at that state of charge, for example: the actual interval resistance reduction rate of the resistance reduction interval from 1000KΩ to 900KΩ. Use multiple actual interval resistance reduction rates to correct the reference interval resistance reduction rate corresponding to the resistance reduction interval to update the reference curve.

[0113] Similarly, for each state of charge, the actual resistance change rate of the defective battery pack of the same model in the process of reducing the insulation resistance to the risk insulation resistance value under the state of charge is determined, and the reference resistance change rate is updated using multiple actual resistance change rates.

[0114] Compared with the online detection method of battery leakage risk in the prior art, the present disclosure can use the obtained current insulation resistance value to determine online the actual interval resistance reduction rate when the battery pack to be tested reduces the preset resistance value each time, and use the comparison results of the actual interval resistance reduction rate and the reference interval resistance reduction rate to perform non-destructive detection of leakage risk, thereby realizing online non-destructive detection without disassembling the battery pack or using professional testing equipment, reducing testing costs, and solving the problem of high cost of detecting battery leakage risks.

[0115] Based on the same inventive concept, an online detection device for battery leakage risk corresponding to the online detection method for battery leakage risk is also provided in the embodiment of the present disclosure. Since the principle of solving the problem by the device in the embodiment of the present disclosure is similar to the above-mentioned online detection method for battery leakage risk in the embodiment of the present disclosure, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0116] Please refer to Figure 2, which is a schematic diagram of the structure of an online detection device for battery leakage risk provided by an embodiment of the present disclosure. As shown in Figure 2, the online detection device 200 for battery leakage risk includes:

[0117] Theoretical value calculation module 201 is used to obtain the current insulation resistance of the battery pack to be tested online. When the current insulation resistance drops to the risk insulation resistance, the theoretical resistance reduction value is determined based on the theoretical resistance change rate under different charge states and the actual process duration corresponding to the different charge states during the resistance reduction process;

[0118] The numerical comparison module 202 is used to compare the theoretical resistance reduction value with the risk insulation resistance value. If the theoretical resistance reduction value is less than the risk insulation resistance value, when the current insulation resistance value is reduced by a preset resistance value, the actual interval resistance reduction rate corresponding to the current resistance reduction process is determined;

[0119] The interval risk determination module 203 is used to compare the actual interval resistance reduction rate with the reference resistance reduction rate corresponding to the reference curve, and determine the interval leakage risk corresponding to the current resistance reduction process based on the comparison result;

[0120] A loop calculation module 204 is configured to, when the judgment condition is not met, use the insulation resistance after the preset resistance is reduced as the new current insulation resistance, and return to the step of determining the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance is reduced by the preset resistance;

[0121] The comprehensive risk determination module 205 is configured to determine the final battery leakage risk of the battery pack to be tested based on the interval leakage risks corresponding to the multiple resistance reduction processes when the judgment condition is met.

[0122] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0123] In the several embodiments provided in the present disclosure, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. There may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interface, indirect coupling or communication connection of devices or units, which may be electrical, mechanical or other forms.

[0124] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0125] In addition, each functional unit in each embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0126] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present disclosure, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0127] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present disclosure, which are used to illustrate the technical solutions of the present disclosure, rather than to limit them. The scope of protection of the present disclosure is not limited thereto. Although the present disclosure has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-mentioned embodiments within the technical scope disclosed in the present disclosure, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims. Industrial Applicability

[0128] The online detection method and device for battery leakage risk provided by the present disclosure can use the acquired current insulation resistance value to determine online the actual interval resistance reduction rate when the battery pack to be tested reduces the preset resistance value each time, and use the comparison results of the actual interval resistance reduction rate and the reference interval resistance reduction rate to perform non-destructive detection of leakage risk, thereby realizing online non-destructive detection without disassembling the battery pack or using professional testing equipment, reducing testing costs, and solving the problem of high cost of detecting battery leakage risks.

Claims

1. An online detection method for battery leakage risk, characterized in that: include: The current insulation resistance of the battery pack to be tested is obtained online, and when the current insulation resistance is reduced to the risk insulation resistance, the reference resistance reduction value is determined according to the reference resistance change rate under different charge states and the actual process duration corresponding to the different charge states during the resistance reduction process; Compare the reference resistance reduction value with the risk insulation resistance value, and if the reference resistance reduction value is less than the risk insulation resistance value, determine the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance value is reduced by a preset resistance value; Comparing the actual interval resistance reduction rate with the corresponding reference interval resistance reduction rate in the reference curve, and determining the interval leakage risk corresponding to the current resistance reduction process according to the comparison result; When the judgment condition is not met, the insulation resistance after the preset resistance is reduced is used as the new current insulation resistance, and the step of determining the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance is reduced by the preset resistance is returned to be executed; When the judgment condition is met, the final battery leakage risk of the battery pack to be tested is determined according to the interval leakage risks corresponding to the multiple resistance reduction processes.

2. The method according to claim 1, characterized in that Determining the reference resistance reduction value according to the reference resistance change rate under different charge states and the actual process duration under different charge states during the resistance reduction process includes: For each state of charge, determine the product of the reference resistance change rate corresponding to the state of charge and the actual process duration corresponding to the state of charge; The sum of the products at different states of charge is taken as the reference resistance reduction value.

3. The method according to claim 1, characterized in that The reference curve includes a first reference curve and a second reference curve, the first reference curve includes a resistance reduction rate in a first reference interval corresponding to the current resistance reduction process, the second reference curve includes a resistance reduction rate in a second reference interval corresponding to the current resistance reduction process, the state of charge corresponding to the first reference curve is higher than the state of charge corresponding to the second reference curve, and determining the leakage risk in the interval corresponding to the current resistance reduction process according to the comparison result includes: If the actual interval resistance reduction rate is less than the second reference interval resistance reduction rate, it is determined that the interval leakage risk of this resistance reduction process is low; If the actual interval resistance reduction rate is less than the first reference interval resistance reduction rate and greater than or equal to the second reference interval resistance reduction rate, it is determined that the interval leakage risk of this resistance reduction process is medium; If the actual interval resistance reduction rate is greater than or equal to the first reference interval resistance reduction rate, it is determined that the leakage risk of the interval where the resistance is reduced this time is high.

4. The method according to claim 1, characterized in that The determining of the actual interval resistance reduction rate corresponding to the current resistance reduction process includes: The ratio of the preset resistance value to the time required for the current resistance reduction process is used as the actual interval resistance reduction rate.

5. The method according to claim 1, characterized in that After comparing the reference resistance reduction value with the risk insulation resistance value, the method further includes: If the ratio of the reference resistance reduction value to the risk insulation resistance value is less than a set threshold, determining whether the voltage and temperature of the battery cell in the battery pack to be tested are set values; If it is the set value, it is determined that the battery pack to be tested has a sealing problem; If it is not the set value, it is determined that the battery pack to be tested has a risk of battery leakage, so as to further determine the severity of the leakage risk.

6. The method according to claim 1, characterized in that The method further comprises: If the reference resistance reduction value is greater than or equal to the risk insulation resistance value, the severity of the final battery leakage risk of the battery pack to be tested is low.

7. The method according to claim 1, characterized in that Before the online acquisition of the current insulation resistance value of the battery pack to be detected, the method further includes: Acquire multiple defective batteries with leakage risk, adjust the multiple defective batteries to different charge states respectively and pack them respectively to obtain defective battery packs with different charge states; For each defective battery pack, monitor the insulation resistance of the defective battery pack, and record the theoretical total time required for the defective battery pack to reduce from the initial insulation resistance to the target insulation resistance, the theoretical resistance change value during the reduction process, and the theoretical interval time required for each reduction in the preset resistance; Determine a reference resistance change rate of the state of charge corresponding to the defective battery pack according to the theoretical total time and the theoretical resistance change value; According to the theoretical interval duration and the preset resistance value, a reference curve corresponding to the defective battery pack is determined.

8. The method according to claim 1, characterized in that The method further comprises: When the current insulation resistance value decreases to the risk insulation resistance value, determining the actual resistance change rate according to the total insulation resistance change value during the decrease process and the time required for the decrease process; The actual resistance change rate is compared with the reference resistance change rate, and the battery leakage risk of the battery pack to be tested is determined according to the comparison result.

9. The method according to claim 1, characterized in that: The method further comprises: The reference curve is updated using the actual interval resistance reduction rate of the battery pack to be tested during different resistance reduction processes; The reference resistance change rate is updated by using the actual resistance change rate in the process of reducing the current insulation resistance to the risk insulation resistance.

10. An online detection device for battery leakage risk, characterized in that: include: The theoretical value calculation module is used to obtain the current insulation resistance of the battery pack to be tested online, and when the current insulation resistance is reduced to the risk insulation resistance, the reference resistance reduction value is determined according to the reference resistance change rate under different charge states and the actual process duration corresponding to the different charge states during the resistance reduction process; A numerical comparison module, used for comparing the reference resistance reduction value with the risk insulation resistance value, and if the reference resistance reduction value is less than the risk insulation resistance value, then when the current insulation resistance value is reduced by a preset resistance value, determining the actual interval resistance reduction rate corresponding to the current resistance reduction process; An interval risk determination module, used to compare the actual interval resistance reduction rate with the reference interval resistance reduction rate corresponding to the reference curve, and determine the interval leakage risk corresponding to the current resistance reduction process according to the comparison result; A loop calculation module, for, when the judgment condition is not met, using the insulation resistance after the preset resistance is reduced as the new current insulation resistance, and returning to execute the step of determining the actual interval resistance reduction rate corresponding to the current resistance reduction process when the current insulation resistance is reduced by the preset resistance; The comprehensive risk determination module is used to determine the final battery leakage risk of the battery pack to be tested according to the interval leakage risk corresponding to multiple resistance reduction processes when the judgment conditions are met.

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